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sfc: Refactor struct efx_tx_buffer to use a flags field
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Add a flags field to struct efx_tx_buffer, replacing the
continuation and map_single booleans.

Since a single descriptor cannot be both a TSO header and the last
descriptor for an skb, unionise efx_tx_buffer::{skb,tsoh} and add
flags for validity of these fields.

Clear all flags in free buffers (whereas previously the continuation
flag would be set).

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
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Ben Hutchings committed Aug 24, 2012
1 parent 8f4cccb commit 7668ff9
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Showing 3 changed files with 53 additions and 56 deletions.
27 changes: 14 additions & 13 deletions drivers/net/ethernet/sfc/net_driver.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -91,29 +91,30 @@ struct efx_special_buffer {
};

/**
* struct efx_tx_buffer - An Efx TX buffer
* @skb: The associated socket buffer.
* Set only on the final fragment of a packet; %NULL for all other
* fragments. When this fragment completes, then we can free this
* skb.
* @tsoh: The associated TSO header structure, or %NULL if this
* buffer is not a TSO header.
* struct efx_tx_buffer - buffer state for a TX descriptor
* @skb: When @flags & %EFX_TX_BUF_SKB, the associated socket buffer to be
* freed when descriptor completes
* @tsoh: When @flags & %EFX_TX_BUF_TSOH, the associated TSO header structure.
* @dma_addr: DMA address of the fragment.
* @flags: Flags for allocation and DMA mapping type
* @len: Length of this fragment.
* This field is zero when the queue slot is empty.
* @continuation: True if this fragment is not the end of a packet.
* @unmap_single: True if dma_unmap_single should be used.
* @unmap_len: Length of this fragment to unmap
*/
struct efx_tx_buffer {
const struct sk_buff *skb;
struct efx_tso_header *tsoh;
union {
const struct sk_buff *skb;
struct efx_tso_header *tsoh;
};
dma_addr_t dma_addr;
unsigned short flags;
unsigned short len;
bool continuation;
bool unmap_single;
unsigned short unmap_len;
};
#define EFX_TX_BUF_CONT 1 /* not last descriptor of packet */
#define EFX_TX_BUF_SKB 2 /* buffer is last part of skb */
#define EFX_TX_BUF_TSOH 4 /* buffer is TSO header */
#define EFX_TX_BUF_MAP_SINGLE 8 /* buffer was mapped with dma_map_single() */

/**
* struct efx_tx_queue - An Efx TX queue
Expand Down
4 changes: 3 additions & 1 deletion drivers/net/ethernet/sfc/nic.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -401,8 +401,10 @@ void efx_nic_push_buffers(struct efx_tx_queue *tx_queue)
++tx_queue->write_count;

/* Create TX descriptor ring entry */
BUILD_BUG_ON(EFX_TX_BUF_CONT != 1);
EFX_POPULATE_QWORD_4(*txd,
FSF_AZ_TX_KER_CONT, buffer->continuation,
FSF_AZ_TX_KER_CONT,
buffer->flags & EFX_TX_BUF_CONT,
FSF_AZ_TX_KER_BYTE_COUNT, buffer->len,
FSF_AZ_TX_KER_BUF_REGION, 0,
FSF_AZ_TX_KER_BUF_ADDR, buffer->dma_addr);
Expand Down
78 changes: 36 additions & 42 deletions drivers/net/ethernet/sfc/tx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,25 +39,25 @@ static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
buffer->unmap_len);
if (buffer->unmap_single)
if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
DMA_TO_DEVICE);
else
dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
DMA_TO_DEVICE);
buffer->unmap_len = 0;
buffer->unmap_single = false;
}

if (buffer->skb) {
if (buffer->flags & EFX_TX_BUF_SKB) {
(*pkts_compl)++;
(*bytes_compl) += buffer->skb->len;
dev_kfree_skb_any((struct sk_buff *) buffer->skb);
buffer->skb = NULL;
netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
"TX queue %d transmission id %x complete\n",
tx_queue->queue, tx_queue->read_count);
}

buffer->flags &= EFX_TX_BUF_TSOH;
}

/**
Expand Down Expand Up @@ -89,14 +89,14 @@ static void efx_tsoh_heap_free(struct efx_tx_queue *tx_queue,
static void efx_tsoh_free(struct efx_tx_queue *tx_queue,
struct efx_tx_buffer *buffer)
{
if (buffer->tsoh) {
if (buffer->flags & EFX_TX_BUF_TSOH) {
if (likely(!buffer->tsoh->unmap_len)) {
buffer->tsoh->next = tx_queue->tso_headers_free;
tx_queue->tso_headers_free = buffer->tsoh;
} else {
efx_tsoh_heap_free(tx_queue, buffer->tsoh);
}
buffer->tsoh = NULL;
buffer->flags &= ~EFX_TX_BUF_TSOH;
}
}

Expand Down Expand Up @@ -163,7 +163,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
unsigned int len, unmap_len = 0, fill_level, insert_ptr;
dma_addr_t dma_addr, unmap_addr = 0;
unsigned int dma_len;
bool unmap_single;
unsigned short dma_flags;
int q_space, i = 0;
netdev_tx_t rc = NETDEV_TX_OK;

Expand All @@ -190,7 +190,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
* since this is more efficient on machines with sparse
* memory.
*/
unmap_single = true;
dma_flags = EFX_TX_BUF_MAP_SINGLE;
dma_addr = dma_map_single(dma_dev, skb->data, len, PCI_DMA_TODEVICE);

/* Process all fragments */
Expand Down Expand Up @@ -234,10 +234,8 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
insert_ptr = tx_queue->insert_count & tx_queue->ptr_mask;
buffer = &tx_queue->buffer[insert_ptr];
efx_tsoh_free(tx_queue, buffer);
EFX_BUG_ON_PARANOID(buffer->tsoh);
EFX_BUG_ON_PARANOID(buffer->skb);
EFX_BUG_ON_PARANOID(buffer->flags);
EFX_BUG_ON_PARANOID(buffer->len);
EFX_BUG_ON_PARANOID(!buffer->continuation);
EFX_BUG_ON_PARANOID(buffer->unmap_len);

dma_len = efx_max_tx_len(efx, dma_addr);
Expand All @@ -247,13 +245,14 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
/* Fill out per descriptor fields */
buffer->len = dma_len;
buffer->dma_addr = dma_addr;
buffer->flags = EFX_TX_BUF_CONT;
len -= dma_len;
dma_addr += dma_len;
++tx_queue->insert_count;
} while (len);

/* Transfer ownership of the unmapping to the final buffer */
buffer->unmap_single = unmap_single;
buffer->flags = EFX_TX_BUF_CONT | dma_flags;
buffer->unmap_len = unmap_len;
unmap_len = 0;

Expand All @@ -264,14 +263,14 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
len = skb_frag_size(fragment);
i++;
/* Map for DMA */
unmap_single = false;
dma_flags = 0;
dma_addr = skb_frag_dma_map(dma_dev, fragment, 0, len,
DMA_TO_DEVICE);
}

/* Transfer ownership of the skb to the final buffer */
buffer->skb = skb;
buffer->continuation = false;
buffer->flags = EFX_TX_BUF_SKB | dma_flags;

netdev_tx_sent_queue(tx_queue->core_txq, skb->len);

Expand Down Expand Up @@ -302,7 +301,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)

/* Free the fragment we were mid-way through pushing */
if (unmap_len) {
if (unmap_single)
if (dma_flags & EFX_TX_BUF_MAP_SINGLE)
dma_unmap_single(dma_dev, unmap_addr, unmap_len,
DMA_TO_DEVICE);
else
Expand Down Expand Up @@ -340,7 +339,6 @@ static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
}

efx_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);
buffer->continuation = true;
buffer->len = 0;

++tx_queue->read_count;
Expand Down Expand Up @@ -484,7 +482,7 @@ int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
{
struct efx_nic *efx = tx_queue->efx;
unsigned int entries;
int i, rc;
int rc;

/* Create the smallest power-of-two aligned ring */
entries = max(roundup_pow_of_two(efx->txq_entries), EFX_MIN_DMAQ_SIZE);
Expand All @@ -500,8 +498,6 @@ int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
GFP_KERNEL);
if (!tx_queue->buffer)
return -ENOMEM;
for (i = 0; i <= tx_queue->ptr_mask; ++i)
tx_queue->buffer[i].continuation = true;

/* Allocate hardware ring */
rc = efx_nic_probe_tx(tx_queue);
Expand Down Expand Up @@ -546,7 +542,6 @@ void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
unsigned int pkts_compl = 0, bytes_compl = 0;
buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
buffer->continuation = true;
buffer->len = 0;

++tx_queue->read_count;
Expand Down Expand Up @@ -631,7 +626,7 @@ void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
* @in_len: Remaining length in current SKB fragment
* @unmap_len: Length of SKB fragment
* @unmap_addr: DMA address of SKB fragment
* @unmap_single: DMA single vs page mapping flag
* @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0
* @protocol: Network protocol (after any VLAN header)
* @header_len: Number of bytes of header
* @full_packet_size: Number of bytes to put in each outgoing segment
Expand All @@ -651,7 +646,7 @@ struct tso_state {
unsigned in_len;
unsigned unmap_len;
dma_addr_t unmap_addr;
bool unmap_single;
unsigned short dma_flags;

__be16 protocol;
unsigned header_len;
Expand Down Expand Up @@ -833,9 +828,7 @@ static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
efx_tsoh_free(tx_queue, buffer);
EFX_BUG_ON_PARANOID(buffer->len);
EFX_BUG_ON_PARANOID(buffer->unmap_len);
EFX_BUG_ON_PARANOID(buffer->skb);
EFX_BUG_ON_PARANOID(!buffer->continuation);
EFX_BUG_ON_PARANOID(buffer->tsoh);
EFX_BUG_ON_PARANOID(buffer->flags);

buffer->dma_addr = dma_addr;

Expand All @@ -845,7 +838,8 @@ static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
if (dma_len >= len)
break;

buffer->len = dma_len; /* Don't set the other members */
buffer->len = dma_len;
buffer->flags = EFX_TX_BUF_CONT;
dma_addr += dma_len;
len -= dma_len;
}
Expand Down Expand Up @@ -873,12 +867,11 @@ static void efx_tso_put_header(struct efx_tx_queue *tx_queue,
efx_tsoh_free(tx_queue, buffer);
EFX_BUG_ON_PARANOID(buffer->len);
EFX_BUG_ON_PARANOID(buffer->unmap_len);
EFX_BUG_ON_PARANOID(buffer->skb);
EFX_BUG_ON_PARANOID(!buffer->continuation);
EFX_BUG_ON_PARANOID(buffer->tsoh);
EFX_BUG_ON_PARANOID(buffer->flags);
buffer->len = len;
buffer->dma_addr = tsoh->dma_addr;
buffer->tsoh = tsoh;
buffer->flags = EFX_TX_BUF_TSOH | EFX_TX_BUF_CONT;

++tx_queue->insert_count;
}
Expand All @@ -896,11 +889,11 @@ static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
buffer = &tx_queue->buffer[tx_queue->insert_count &
tx_queue->ptr_mask];
efx_tsoh_free(tx_queue, buffer);
EFX_BUG_ON_PARANOID(buffer->skb);
EFX_BUG_ON_PARANOID(buffer->flags & EFX_TX_BUF_SKB);
if (buffer->unmap_len) {
unmap_addr = (buffer->dma_addr + buffer->len -
buffer->unmap_len);
if (buffer->unmap_single)
if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
dma_unmap_single(&tx_queue->efx->pci_dev->dev,
unmap_addr, buffer->unmap_len,
DMA_TO_DEVICE);
Expand All @@ -911,7 +904,7 @@ static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
buffer->unmap_len = 0;
}
buffer->len = 0;
buffer->continuation = true;
buffer->flags = 0;
}
}

Expand All @@ -938,7 +931,7 @@ static void tso_start(struct tso_state *st, const struct sk_buff *skb)

st->out_len = skb->len - st->header_len;
st->unmap_len = 0;
st->unmap_single = false;
st->dma_flags = 0;
}

static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
Expand All @@ -947,7 +940,7 @@ static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0,
skb_frag_size(frag), DMA_TO_DEVICE);
if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
st->unmap_single = false;
st->dma_flags = 0;
st->unmap_len = skb_frag_size(frag);
st->in_len = skb_frag_size(frag);
st->dma_addr = st->unmap_addr;
Expand All @@ -965,7 +958,7 @@ static int tso_get_head_fragment(struct tso_state *st, struct efx_nic *efx,
st->unmap_addr = dma_map_single(&efx->pci_dev->dev, skb->data + hl,
len, DMA_TO_DEVICE);
if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
st->unmap_single = true;
st->dma_flags = EFX_TX_BUF_MAP_SINGLE;
st->unmap_len = len;
st->in_len = len;
st->dma_addr = st->unmap_addr;
Expand All @@ -990,7 +983,7 @@ static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
struct tso_state *st)
{
struct efx_tx_buffer *buffer;
int n, end_of_packet, rc;
int n, rc;

if (st->in_len == 0)
return 0;
Expand All @@ -1008,17 +1001,18 @@ static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,

rc = efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
if (likely(rc == 0)) {
if (st->out_len == 0)
if (st->out_len == 0) {
/* Transfer ownership of the skb */
buffer->skb = skb;

end_of_packet = st->out_len == 0 || st->packet_space == 0;
buffer->continuation = !end_of_packet;
buffer->flags = EFX_TX_BUF_SKB;
} else if (st->packet_space != 0) {
buffer->flags = EFX_TX_BUF_CONT;
}

if (st->in_len == 0) {
/* Transfer ownership of the DMA mapping */
buffer->unmap_len = st->unmap_len;
buffer->unmap_single = st->unmap_single;
buffer->flags |= st->dma_flags;
st->unmap_len = 0;
}
}
Expand Down Expand Up @@ -1195,7 +1189,7 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
unwind:
/* Free the DMA mapping we were in the process of writing out */
if (state.unmap_len) {
if (state.unmap_single)
if (state.dma_flags & EFX_TX_BUF_MAP_SINGLE)
dma_unmap_single(&efx->pci_dev->dev, state.unmap_addr,
state.unmap_len, DMA_TO_DEVICE);
else
Expand Down

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